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  • 1.
    Carlsson, Magnus
    et al.
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Dala Sports Academy, Falun, Sweden..
    Carlsson, Tomas
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Dala Sports Academy, Falun, Sweden..
    Hammarström, Daniel
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Lillehammer University College, Lillehammer, Norway..
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Tonkonogi, Michail
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden. .
    Prediction of race performance of elite cross-country skiers by lean mass2014Inngår i: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 9, nr 6, s. 1040-1045Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: To investigate the relationship between race performance and lean mass (LM) variables, as well as to examine sex differences in body composition in elite-standard cross-country skiers.

    METHODS: Thirty-four elite cross-country skiers (18 men and 16 women) underwent a dual-emission x-ray absorptiometry body composition test to determine LM, fat mass, and bone mineral content. For both sexes, performance data were collected from a sprint prologue and a distance race.

    RESULTS: The absolute expression of LM variables [whole body (LMWB), upper body (LMUB), and lower body (LMLB)] was significantly correlated with finishing time in the sprint prologue independent of sex. Distance-race performance was significantly related to LMWB, LMUB, and LMLB in women; however, no correlation was found in men. Men had a significantly higher LM and lower fat mass, independent of expression (absolute or relative), for the whole body, arms, trunk, and legs, except for the absolute fat mass in the trunk.

    CONCLUSIONS: The absolute expressions of LMWB, LMUB, and LMLB were significant predictors of sprint-prologue performance in both sexes, as well as of distance-race performance in women only. Compared with women, male skiers have a higher LM in the body segments that are major contributors to propelling forces. These results suggest that muscle mass in the lower and upper body is equally important for race performance; thus, more focus of elite skiers' training should be directed to increasing whole-body muscle mass to improve their competitive performance capability.

  • 2.
    Carlsson, Magnus
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Carlsson, Tomas
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Hammarström, Daniel
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Tonkonogi, Michail
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Time Trials Predict the Competitive Performance Capacity of Junior Cross-Country Skiers2014Inngår i: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 9, nr 1, s. 12-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: This study investigated whether there is a correlation between time-trial performance and competitive performance capacity of male and female junior cross-country skiers and sought to explain gender-specific competitive performance capacity through multiple regression modeling.

    METHODS: The International Ski Federation's (FIS) junior ranking points for distance (FISdist) and sprint (FISsprint) competitions were used as performance parameters. A total of 38 elite junior (18.5 ± 1.0 years old) cross-country skiers (24 men and 14 women) completed three time-trial tests: a 3 km level running time trial (TTRun), a 2 km moderate uphill (1.2º slope) roller skiing time trial using the double poling technique (TTDP), and a 2 km uphill (2.8º slope) roller skiing time trial using the diagonal stride technique (TTDiag). The correlations were investigated using Pearson correlation analysis, and regression models were created using multiple linear regression analysis.

    RESULTS: For men, FISsprint and FISdist were correlated with the times for TTRun, TTDP, and TTDiag (all P < 0.001). For women, FISsprint was correlated with the times for TTRun (P < 0.05), TTDP (P < 0.01), and TTDiag (P < 0.01), whereas FISdist was correlated with the times for TTDP (P < 0.01) and TTDiag (P < 0.05). The models developed for FISdist and FISsprint explained 73.9-82.3% of the variance in the performance capacity of male junior cross-country skiers. No statistically valid regression model was found for the women.

    CONCLUSIONS: The running and roller skiing time trials are useful for the accurate prediction of the performance capacity of junior cross-country skiers.

  • 3.
    Carlsson, Magnus
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Carlsson, Tomas
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Hammarström, Daniel
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Tiivel, Toomas
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Winternet, Boden, Sweden..
    Tonkonogi, Michail
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Validation of physiological tests in relation to competitive performances in elite male distance cross-country skiing2012Inngår i: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287, Vol. 26, nr 6, s. 1496-1504Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of the present study was to establish which physiological test parameters reflects the distance performances in the Swedish National Championships in cross-country skiing (SNC) and the International Ski Federation's ranking points for distance performances (FISdist). The present study also aimed to create multiple regression models to describe skiing performance for the SNC distance races and International Ski Federation's (FIS) ranking. Twelve male, Swedish, national elite, cross-country skiers (maximal oxygen consumption [V̇O2max] = 5.34 ± 0.34 L·min) volunteered to participate in the study. Their results in the 2008 SNC (15 km race [SNC15] and 30 km race [SNC30]) and FISdist points were used as performance data. On the week preceding the Championship, subjects completed a test battery consisting of 7 physiological tests: isokinetic knee extension peak torque (PT), vertical jumps (VJ), lactate threshold (LT), V̇O2max, and 3 double poling tests of different durations (DP20, DP60, and DP360). Correlations were established using Pearson's correlation analysis, and models to describe skiing performance were created using standard multiple linear regression analysis. Significant correlations were found between the performance parameters and test parameters derived from LT, V̇O2max, and DP60 tests. No correlations with any performance parameter were found for PT, VJ, DP20, and DP360 tests. For FISdist and SNC15, the models explain 81% and 78% of the variance in performance, respectively. No statistically valid regression model was found for SNC30. The results of this study imply that the physiological demands in male elite distance cross-country skiing performances are different in different events. To adequately evaluate a skier's performance ability in distance cross-country skiing, it is necessary to use test parameters and regression models that reflect the specific performance.

  • 4.
    Carlsson, Magnus
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Dala Sports Academy, Falun, Sweden..
    Carlsson, Tomas
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Dala Sports Academy, Falun, Sweden..
    Knutsson, Magnus
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Dala Sports Academy, Falun, Sweden..
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Winternet, Boden, Sweden.
    Tonkonogi, Michail
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Oxygen uptake at different intensities and sub-techniques predicts sprint performance in elite male cross-country skiers2014Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 114, nr 12, s. 2587-2595Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: To investigate the relationship between sprint-prologue performance (using the classical technique) and the oxygen uptake at the lactate threshold (V̇O2obla), maximal oxygen uptake (V̇O2max), and mean oxygen uptake during double poling (V̇O2dp).

    METHODS: Eight elite male cross-country skiers [age 24.8 ± 4.8 years, (mean ± SD)] completed two treadmill roller-skiing tests using the diagonal-stride technique and a 60 s double-poling test on a ski-ergometer to determine their V̇O2obla, V̇O2max, and V̇O2dp. Performance data were generated from a 1.25 km sprint prologue. Power-function modelling was used to predict the skiers' race speeds based on the oxygen-uptake variables and body mass.

    RESULTS: There were correlations between the race speed and the absolute expression of the V̇O2obla (r = 0.79, P = 0.021), V̇O2max (r = 0.86, P = 0.0069), and V̇O2dp (r = 0.94, P = 0.00062). The following power-function models were established for race-speed prediction: 1.09 · V̇O2obla(0.21), 1.05 · V̇O2max(0.21), and 1.19 · V̇O2dp(0.20); these models explained 60 % (P = 0.024), 73 % (P = 0.0073), and 87 % (P = 0.00073), respectively, of the variance in the race speed. However, body mass did not contribute to any of the models (P = 0.97, 0.88, and 0.21, respectively).

    CONCLUSIONS: Oxygen uptake at different intensities and sub-techniques is an indicator of elite male sprint-prologue performance. The absolute expression of the investigated oxygen-uptake variables should be used when evaluating elite male sprint-prologue performances; if skiers oxygen uptake differs by 1 %, their performances will likely differ by 0.2 % in favour of the skier with higher oxygen uptake.

  • 5.
    Carlsson, Magnus
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. School of Education, Health and Social Studies, Dalarna University, Falun, Sweden; Dala Sports Academy, Falun, Sweden.
    Carlsson, Tomas
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. School of Education, Health and Social Studies, Dalarna University, Falun, Sweden; Dala Sports Academy, Falun, Sweden.
    Wedholm, Lars
    School of Education, Health and Social Studies, Dalarna University, Falun, Sweden; Dala Sports Academy, Falun, Sweden.
    Nilsson, Mattias
    Regional Sports Federation of Dalarna, Falun, Sweden.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Tonkonogi, Michail
    School of Education, Health and Social Studies, Dalarna University, Falun, Sweden.
    Physiological demands of competitive sprint and distance performance in elite female cross-country skiing2016Inngår i: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287, Vol. 30, nr 8, s. 2138-2144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose was to investigate the relationship between elite females' competitive performance capability in sprint and distance cross-country skiing and the variables of gross efficiency (GE), work rate at the onset of blood-lactate accumulation (OBLA4mmol), maximal oxygen uptake (V[Combining Dot Above]O2max), maximal speed (Vmax), and peak upper-body oxygen uptake (V[Combining Dot Above]O2peak). Ten elite female cross-country skiers (age 24.5 ± 2.8 years) completed treadmill roller-skiing tests to determine GE, OBLA4mmol, and V[Combining Dot Above]O2max using the diagonal-stride technique as well as Vmax and V[Combining Dot Above]O2peak using the double-poling technique. International Ski Federations ranking points for sprint (FISsprint) and distance (FISdist) races were used as competitive performance data. There were correlations between the FISsprint and the V[Combining Dot Above]O2max expressed absolutely (p = 0.0040), Vmax (p = 0.012), and V[Combining Dot Above]O2peak expressed absolutely (p < 0.001) and as a simple ratio-standard (p = 0.049). The FISdist were correlated with OBLA4mmol (p = 0.048), V[Combining Dot Above]O2max expressed absolutely (L·min) (p = 0.015) and as a simple ratio-standard (p = 0.046), and V[Combining Dot Above]O2peak expressed absolutely (p = 0.036) and as a simple ratio-standard (ml·min·kg) (p = 0.040). The results demonstrate that the physiological abilities reflected by V[Combining Dot Above]O2max and V[Combining Dot Above]O2peak are indicators of competitive sprint and distance performance in elite female cross-country skiing. In addition, the ability to generate a high Vmax indicates the performance in sprint races, whereas the skier's OBLA4mmol reflects the performance capability in distance races. Based on the results, when evaluating the performance capacity of elite female cross-country skiers, it is recommended to use physiological variables that reflect competitive performance.

  • 6.
    Carlsson, Tomas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden; Dala Sports Academy, Falun, Sweden..
    Carlsson, Magnus
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden; Dala Sports Academy, Falun, Sweden..
    Felleki, Majbritt
    Department of Technology and Business Studies, Dalarna University, Borlänge, Sweden..
    Hammarström, Daniel
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Dala Sports Academy, Falun, Sweden..
    Heil, Daniel
    Department of Health and Human Development, Montana State University, Bozeman, USA..
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Winternet, Boden, Sweden.
    Tonkonogi, Michail
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Scaling maximal oxygen uptake to predict performance in elite-standard men cross-country skiers2013Inngår i: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 31, nr 16, s. 1753-1760Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to: 1) establish the optimal body-mass exponent for maximal oxygen uptake (VO2max) to indicate performance in elite-standard men cross-country skiers; and 2) evaluate the influence of course inclination on the body-mass exponent. Twelve elite-standard men skiers completed an incremental treadmill roller-skiing test to determine VO2max and performance data came from the 2008 Swedish National Championship 15-km classic-technique race. Log-transformation of power-function models was used to predict skiing speeds. The optimal models were found to be: Race speed = 7.86 · VO2max · m (-0.48) and Section speed = 5.96 · VO2max · m (-(0.38 + 0.03 · α)) · e(-0.003 · Δ) (where m is body mass, α is the section's inclination and Δ is the altitude difference of the previous section), that explained 68% and 84% of the variance in skiing speed, respectively. A body-mass exponent of 0.48 (95% confidence interval: 0.19 to 0.77) best described VO2max as an indicator of performance in elite-standard men skiers. The confidence interval did not support the use of either "1" (simple ratio-standard scaled) or "0" (absolute expression) as body-mass exponents for expressing VO2max as an indicator of performance. Moreover, results suggest that course inclination increases the body-mass exponent for VO2max.

  • 7.
    Carlsson, Tomas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Carlsson, Magnus
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Hammarström, Daniel
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden..
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Winternet, Boden, Sweden..
    Tonkonogi, Michail
    Department of Health and Social Sciences, Dalarna University, Falun, Sweden. Olympiatoppen, Oslo, Norway..
    Scaling of upper-body power output to predict time-trial roller skiing performance2013Inngår i: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 31, nr 6, s. 582-588Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of the present study was to establish the most appropriate allometric model to predict mean skiing speed during a double-poling roller skiing time-trial using scaling of upper-body power output. Forty-five Swedish junior cross-country skiers (27 men and 18 women) of national and international standard were examined. The skiers, who had a body mass (m) of 69.3 +/- 8.0 kg (mean +/- s), completed a 120-s double-poling test on a ski ergometer to determine their mean upper-body power output (W). Performance data were subsequently obtained from a 2-km time-trial, using the double-poling technique, to establish mean roller skiing speed. A proportional allometric model was used to predict skiing speed. The optimal model was found to be: Skiing speed = 1.057 · W0.556 · m-0.315, which explained 58.8% of the variance in mean skiing speed (< 0.001). The 95% confidence intervals for the scaling factors ranged from 0.391 to 0.721 for W and from 0.626 to 0.004 for m. The results in this study suggest that allometric scaling of upper-body power output is preferable for the prediction of performance of junior cross-country skiers rather than absolute expression or simple ratio-standard scaling of upper-body power output.

  • 8.
    Carlsson, Tomas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. School of Education, Health and Social Studies, Dalarna University, Falun, Sweden..
    Carlsson, Magnus
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. School of Education, Health and Social Studies, Dalarna University, Falun, Sweden..
    Hammarström, Daniel
    The Lillehammer Research Center for Medicine and Exercise Physiology, Lillehammer University College, Lillehammer, Norway..
    Rønnestad, Bent
    The Lillehammer Research Center for Medicine and Exercise Physiology, Lillehammer University College, Lillehammer, Norway..
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Tonkonogi, Michail
    School of Education, Health and Social Studies, Dalarna University, Falun, Sweden..
    Optimal V̇O2max-to-mass ratio for predicting 15-km performance among elite male cross-country skiersManuskript (preprint) (Annet vitenskapelig)
  • 9.
    Carlsson, Tomas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin. School of Education, Health and Social Studies, Dalarna University.
    Carlsson, Magnus
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin. School of Education, Health and Social Studies, Dalarna University.
    Hammarström, Daniel
    Rønnestad, Bent R
    Malm, Christer B.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Tonkonogi, Michail
    Optimal Formula V̇O 2max -to-mass ratio for performance among elite male cross-country skiers2015Inngår i: Open Access Journal of Sports Medicine, ISSN 1179-1543, E-ISSN 1179-1543, Vol. 6, s. 353-360Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was 1) to validate the 0.5 body-mass exponent for maximal. oxygen uptake [Formula: see text] as the optimal predictor of performance in a 15 km classical-technique skiing competition among elite male cross-country skiers and 2) to evaluate the influence of distance covered on the body-mass exponent for [Formula: see text] among elite male skiers. Twenty-four elite male skiers (age: 21.4±3.3 years [mean ± standard deviation]) completed an incremental treadmill roller-skiing test to determine their [Formula: see text]. Performance data were collected from a 15 km classical-technique cross-country skiing competition performed on a 5 km course. Power-function modeling (ie, an allometric scaling approach) was used to establish the optimal body-mass exponent for [Formula: see text] to predict the skiing performance. The optimal power-function models were found to be [Formula: see text] and [Formula: see text], which explained 69% and 81% of the variance in skiing speed, respectively. All the variables contributed to the models. Based on the validation results, it may be recommended that [Formula: see text] divided by the square root of body mass (mL · min(-1) · kg(-0.5)) should be used when elite male skiers' performance capability in 15 km classical-technique races is evaluated. Moreover, the body-mass exponent for [Formula: see text] was demonstrated to be influenced by the distance covered, indicating that heavier skiers have a more pronounced positive pacing profile (ie, race speed gradually decreasing throughout the race) compared to that of lighter skiers.

  • 10. Ekblom, B
    et al.
    Ekblom, O
    Malm, Christer
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Anatomi.
    Infectious episodes before and after a marathon race.2006Inngår i: Scandinavian Journal of Medicine & Science in Sports, ISSN 0905-7188, Vol. 16, nr 4, s. 287-93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to investigate the incidence of self-reported infectious episodes (IE) during 3 weeks before (pre-IE) and 3 weeks after (post-IE) a marathon race and relate these figures to training status, running time, socioeconomic and demographic factors. Two questionnaires, including questions about important factors for IE incidence, were given to a representative cohort of 1694 runners (17% of all finishers) in the Stockholm Marathon 2000. Pre-IE incidence in the cohort was 17% with no difference between women and men. Post-IE incidence in the whole cohort was 19% with no significant (P>0.05) difference between women and men. The post-IE incidence in runners without a pre-IE was 16% (P>0.05 to pre-IE incidence). In the group of runners with pre-IE, 33% experienced an IE after the race also (P<0.05 to Pre-IE incidence). A logistic regression analysis showed that younger age and pre race health status and, for men only, experienced nausea during and after the race were depended factors explaining post-IE incidence. Younger runners were more prone to experience IE both before and after the race. There was no relation between training volume 6 months before the race, finishing time and socioeconomic and demographic factors and pre-IE or post-IE. This study does not support the theory of increased infection rate after exhaustive long-distance running ("The Open Window Theory") in recreational runners, but suggests that the sometimes experienced increased rate of infections among athletes can be caused by strenuous exercise too soon after an infection.

  • 11. Ekblom, Örjan
    et al.
    Ekblom, Björn
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Immunological alterations used to predict infections in response to strenuous physical training2011Inngår i: Military medicine, ISSN 0026-4075, E-ISSN 1930-613X, Vol. 176, nr 7, s. 785-790Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to screen leukocyte cell surface markers to identify possible predictors for infection related to physical training. Ten healthy soldiers (mean age, 19.1; mean body mass, 77.4 kg; mean VO2 peak, 4.54 L min(-1)/58.6 mL min(-1) kg(-1)) were included. Blood samples were collected and number of infections recorded before and after a 6-day training course. White blood cell distributions and expression of surface receptors changed during training. Before training, expression of CD3 on CD8+ lymphocytes and percent CD8+CD3 lymphocytes was lower, whereas CD4/CD8 ratio was higher among subjects who failed compared to those who completed the training. A subclinical infection before the start of the military training may alter the CD4/CD8 ratio. Prediction of future infections may be possible from pre-exercise immunological status, findings useful in military settings and exercise, where sudden infections may result in severe consequences.

  • 12.
    Eriksson, Anders
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Anatomi.
    Kadi, Fawzi
    Malm, Christer
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Anatomi.
    Thornell, Lars-Eric
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Anatomi.
    Skeletal muscle morphology in power-lifters with and without anabolic steroids.2005Inngår i: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 124, nr 2, s. 167-175Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The morphological appearance of the vastus lateralis (VL) muscle from high-level power-lifters on long-term anabolic steroid supplementation (PAS) and power-lifters never taking anabolic steroids (P) was compared. The effects of long- and short-term supplementation were compared. Enzyme-immunohistochemical investigations were performed to assess muscle fiber type composition, fiber area, number of myonuclei per fiber, internal myonuclei, myonuclear domains and proportion of satellite cells. The PAS group had larger type I, IIA, IIAB and IIC fiber areas (p<0.05). The number of myonuclei/fiber and the proportion of central nuclei were significantly higher in the PAS group (p<0.05). Similar results were seen in the trapezius muscle (T) but additionally, in T the proportion of fibers expressing developmental myosin isoforms was higher in the PAS group compared to the P group. Further, in VL, the PAS group had significantly larger nuclear domains in fibers containing > or = 5 myonuclei. The results of AS on VL morphology in this study were similar to previously reported short-term effects of AS on VL. The initial effects from AS appear to be maintained for several years.

  • 13.
    Hadrevi, Jenny
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Hellström, Fredrik
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Kieselbach, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Pedrosa-Domellöf, Fatima
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Protein differences between human trapezius and vastus lateralis muscles determined with a proteomic approach2011Inngår i: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 12, nr 181, s. 11-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: The trapezius muscle is a neck muscle that is susceptible to chronic pain conditions associated with repetitive tasks, commonly referred to as chronic work-related myalgia, hence making the trapezius a muscle of clinical interest. To provide a basis for further investigations of the proteomic traits of the trapezius muscle in disease, two-dimensional difference gel electrophoresis (2D-DIGE) was performed on the healthy trapezius using vastus lateralis as a reference. To obtain as much information as possible from the vast proteomic data set, both one-way ANOVA, with and without false discovery rate (FDR) correlation, and partial least square projection to latent structures with discriminant analysis (PLS-DA) were combined to compare the outcome of the analysis.

    Results: The trapezius and vastus lateralis showed significant differences in metabolic, contractile and regulatory proteins, with different results depending on choice of statistical approach and pre-processing technique. Using the standard method, FDR correlated one-way ANOVA, 42 protein spots differed significantly in abundance between the two muscles. Complementary analysis using immunohistochemistry and western blot confirmed the results from the 2D-DIGE analysis.

    Conclusions: The proteomic approach used in the present study combining 2D-DIGE and multivariate modelling provided a more comprehensive comparison of the protein profiles of the human trapezius and vastus lateralis muscle, than previously possible to obtain with immunohistochemistry or SDS-PAGE alone. Although 2D-DIGE has inherent limitations it is particularly useful to comprehensively screen for important structural and metabolic proteins, and appears to be a promising tool for future studies of patients suffering from chronic work related myalgia or other muscle diseases.

  • 14.
    Hult, Andreas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Oldenborg, Per-Arne
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Histologi med cellbiologi.
    Transfusion of cryopreserved human red blood cells into healthy humans is associated with rapid extravascular hemolysis without a proinflammatory cytokine response2013Inngår i: Transfusion, ISSN 0041-1132, E-ISSN 1537-2995, Vol. 53, nr 1, s. 28-33Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Transfusion of stored red blood cells (RBCs) can be associated with adverse side effects. Recent studies in mice transfused with stored RBCs showed that a strong proinflammatory cytokine storm was induced due to extravascular hemolysis already at 2 hours after transfusion. Therefore, we here investigated if transfusion of 2 units of cryopreserved autologous RBCs induced a proinflammatory response in healthy human volunteers.

    STUDY DESIGN AND METHODS: Two units of autologous RBCs, cryopreserved for 16 weeks, were transfused into 10 healthy human volunteers. Serum and blood samples taken at 2 hours before and at 2 and 48 hours after transfusion were analyzed for signs of extravascular hemolysis and the presence of proinflammatory cytokines.

    RESULTS: At 2 hours after transfusion, transferin-bound serum iron, as well as transferin saturation and total bilirubin, were already significantly increased. These measures all returned back toward that in pretransfusion samples at 48 hours after transfusion. No increases in the production of the proinflammatory cytokines interleukin (IL)-1β, IL-6, IL-8, monocyte chemotactic protein-1, macrophage inflammatory protein-1β, or tumor necrosis factor-α were detected at any time point after transfusion.

    CONCLUSION: Although a significant level of extravascular hemolysis already occurred at 2 hours after transfusion of cryopreserved RBCs, there were no signs of proinflammatory cytokine production up to 48 hours after transfusion.

  • 15.
    Hult, Andreas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Toss, Fredrik
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Oldenborg, Per-Arne
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Phagocytosis of liquid-stored red blood cells in vitro requires serum and macrophage scavenger receptorsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    BACKGROUND: Red blood cells (RBCs) undergo structural and metabolic changes with prolonged storage, which ultimately may decrease their survival after transfusion. Although the storage-induced damage to RBCs has been rather well described biochemically, little is known about the mechanisms underlying the recognition and rapid clearance of the damaged cells by macrophages.STUDY DESIGN AND METHODS: We here used a murine model for cold (+4°C) RBC storage and transfusion. Phagocytosis of human or murine RBCs, liquid stored for 6-8 weeks or 10-14 days respectively, was investigated in murine peritoneal macrophages.RESULTS: The effects of storage on murine RBCs resembled that described for stored human RBCs with regard to decreased adenosine triphosphate (ATP) levels, accumulation of microparticles during storage, and RBC recovery kinetics after transfusion. Under serum-free conditions, phagocytosis of stored human or murine RBCs was reduced by 70-75%, as compared with that in the presence of heat-inactivated fetal calf serum (FCS). Human serum promoted phagocytosis of stored human RBCs similar to that seen with FCS. By blocking macrophage class A scavenger receptors with fucoidan or dextran sulphate, phagocytosis of human or murine RBCs was reduced by more than 90%. Phagocytosis of stored human RBCs was also sensitive to inhibition by the phosphatidylinositol 3 kinase-inhibitor LY294002, the ERK1/2-inhibitor PD98059, or the p38 MAPK-inhibitor SB203580.CONCLUSIONS: RBCs damaged during liquid storage may be recognized by macrophage class A scavenger receptors and serum-dependent mechanisms. This species-independent recognition mechanism may help to further understand the rapid clearance of stored RBCs shortly after transfusion.

  • 16.
    Jakobsson, Johan
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Maximal Lactate Steady State and Lactate Thresholds in the Cross-Country Skiing Sub-Technique Double Poling2019Inngår i: International Journal of Exercise Science, ISSN 1939-795X, Vol. 12, nr 2, s. 57-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The response of blood lactate concentration (BLC) to exercise is a commonly used approach to set training intensities and to determine the anaerobic threshold, which are important in evaluation of endurance exercise performance. The maximal lactate steady state (MLSS) is defined as the highest workload or BLC that can be maintained without continual lactate accumulation over time. The aim of this study was to investigate MLSS in the cross-country skiing sub-technique double poling and to assess the validity of a fixed blood lactate threshold (OBLAand the 45° tangent of the lactate curve). Eight well-trained cross-country skiers (age = 27.6±8.8 years [mean±SD], body mass = 73.9±6.2 kg, height = 179.3±7.0 cm) performed an incremental test to determine OBLA and Individual Anaerobic Threshold (IAnT) and several constant workload tests of 30 min to determine the MLSS. Lactate concentration at MLSS in double poling was 6.7±1.3 mmol·L-1 which was significantly higher compared to OBLA(p<0.001) and IAnT (p<0.01). Despite significant correlations in velocities between MLSS-IAnT and MLSS-OBLA(r=0.95/0.95, p<0.001), significant (p<0.01) differences between MLSS (21.4±2.8 km·h-1) versus IAnT (20.6±3.6 km·h-1) and OBLA(19.9±3.0 km·h-1) was observed. It was concluded that both OBLA and IAnT underestimate MLSS in double poling. A fixed value of 7 mmol·L-1 would be more appropriate in lactate testing of cross-country skiers using the double poling technique, yet dissuaded because of intra-individual variations. Direct determination of MLSS is the recommended approach for useful exercise thresholds, important for training interventions in elite cross-country skiers.

  • 17. Larsson, Helena
    et al.
    Tegern, Matthias
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering. Department of Neurobiology, Care Sciences and Society, Division of Physiotherapy, Karolinska Institutet.
    Monnier, Andreas
    Skoglund, Jörgen
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Helander, Charlotte
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Persson, Emelie
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Broman, Lisbet
    Aasa, Ulrika
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering. Department of Neurobiology, Care Sciences and Society, Division of Physiotherapy, Karolinska Institutet.
    Content Validity Index and Intra- and Inter-Rater Reliability of a New Muscle Strength/Endurance Test Battery for Swedish Soldiers2015Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 7, artikkel-id e0132185Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this study was to examine the content validity of commonly used muscle performance tests in military personnel and to investigate the reliability of a proposed test battery. For the content validity investigation, thirty selected tests were those described in the literature and/or commonly used in the Nordic and North Atlantic Treaty Organization (NATO) countries. Nine selected experts rated, on a four-point Likert scale, the relevance of these tests in relation to five different work tasks: lifting, carrying equipment on the body or in the hands, climbing, and digging. Thereafter, a content validity index (CVI) was calculated for each work task. The result showed excellent CVI (>= 0.78) for sixteen tests, which comprised of one or more of the military work tasks. Three of the tests; the functional lower-limb loading test (the Ranger test), dead-lift with kettlebells, and back extension, showed excellent content validity for four of the work tasks. For the development of a new muscle strength/endurance test battery, these three tests were further supplemented with two other tests, namely, the chins and side-bridge test. The inter-rater reliability was high (intraclass correlation coefficient, ICC2,1 0.99) for all five tests. The intra-rater reliability was good to high (ICC3,1 0.82-0.96) with an acceptable standard error of mean (SEM), except for the side-bridge test (SEM%>15). Thus, the final suggested test battery for a valid and reliable evaluation of soldiers' muscle performance comprised the following four tests; the Ranger test, dead-lift with kettlebells, chins, and back extension test. The criterion-related validity of the test battery should be further evaluated for soldiers exposed to varying physical workload.

  • 18.
    Lindberg, Ann-Sofie
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Gavhed, Desiree
    Karolinska Institutet.
    Oksa, Juha
    Antti, Henrik
    Multivariate statistical assessment of predictors of firefighters' muscular and aerobic work capacityArtikkel i tidsskrift (Fagfellevurdert)
  • 19.
    Lindberg, Ann-Sofie
    et al.
    Winternet, Boden.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Hammarström, Daniel
    Högskolan Dalarna, Falun.
    Oksa, Juha
    Finnish Institute of Occupational Health, Oulu Centre of Expertise for Health and Work Ability Physical Work Capacity team Aapistie.
    Tonkonogi, Michail
    Högskolan Dalarna, Falun.
    Maximal work capacity and performance depends warm-up procedure and environmental but not inspired air temperatures2012Inngår i: Journal of Exercise Physiology - Online, ISSN 1097-9751, E-ISSN 1097-9751, Vol. 15, nr 1, s. 40-46Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to compare peak (VO2 peak) and maximal (VO2 max) oxygen uptake, physical performance, and lactate accumulation [la-] in warm versus cold environments. The influence of inhaled air temperature and different warm up modes on these variables as well as arterial oxygen saturation (SaO2%) and pulmonary function were also studied. Two studies were performed. In study A, 10 males performed maximal exercise tests on a bicycle at +20°C and -12°C. In study B, 8 elite cross-country skiers performed maximal cross-country skiing tests at +13.7ºC. Different warm up modes (continuous and intermittent) and different temperatures of the inhaled air (-8°C and +13°C) were used.  In study A, we found significantly higher VO2 peak, peak carbon dioxide (VCO2 peak), peak ventilation (VE peak) and respiratory exchange ratio (RER) in +20°C compared to -12°C. In study B, we found significantly lower SaO2% at the end compared to the beginning of the maximal performance test. Time to exhaustion (Tex) was significantly longer using intermittent warm up irrespectively of inhaled air temperature. In conclusion, we found that VO2 max was affected by different environmental temperatures but not by different temperatures of the inhaled air and that intermittent warm up increased Tex without affecting VO2 max.

  • 20.
    Lindberg, Ann-Sofie
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Winternet, Boden, Sweden.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Winternet, Boden, Sweden.
    Oksa, Juha
    Gavhed, Desiree
    Self-rated physical loads of work tasks among firefighters2014Inngår i: International Journal of Occupational Safety and Ergonomics, ISSN 1080-3548, E-ISSN 2376-9130, Vol. 20, nr 2, s. 309-321Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objectives: The present study sought to identify firefighters' rated physical demands for the most frequently occuring work tasks and to determine if the ratings differed between full-time and part-time firefighters to help create a basis for the development of physical employment tests for firefighters.

    Methods: An extensive questionnaire was completed by 125 and 68 firefighters in 2000 and 2010, respectively. The data were analysed with the Mann-Whitney U test and binominal test and ranked on the basis of the responses in each category.

    Results: Significant differences were seen between the full-time and part-time firefighters. The work tasks rated as the most physically strenous in terms of aerobic fitness, muscle strength, work posture and body control by most responders were smoke diving upstairs (carrying a hose), victim rescue in different ways, carrying a stretcher over terrain and pulling a hose.

    Conclusions: Physically strenous work tasks should be included in the end-point performance variables used to select physical performance tests for firefighters. The part-time firefighters with no experience in several of the work tasks suggests that work-related exercises are important if both groups of firefighters are expected to do similar work.

  • 21.
    Lindberg, Ann-Sofie
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin. Winternet, Boden, Sweden.
    Oksa, Juha
    Antti, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin. Winternet, Boden, Sweden.
    Multivariate Statistical Assessment of Predictors of Firefighters' Muscular and Aerobic Work Capacity2015Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 3, artikkel-id e0118945Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Physical capacity has previously been deemed important for firefighters physical work capacity, and aerobic fitness, muscular strength, and muscular endurance are the most frequently investigated parameters of importance. Traditionally, bivariate and multivariate linear regression statistics have been used to study relationships between physical capacities and work capacities among firefighters. An alternative way to handle datasets consisting of numerous correlated variables is to use multivariate projection analyses, such as Orthogonal Projection to Latent Structures. The first aim of the present study was to evaluate the prediction and predictive power of field and laboratory tests, respectively, on firefighters' physical work capacity on selected work tasks. Also, to study if valid predictions could be achieved without anthropometric data. The second aim was to externally validate selected models. The third aim was to validate selected models on firefighters' and on civilians'. A total of 38 (26 men and 12 women) + 90 (38 men and 52 women) subjects were included in the models and the external validation, respectively. The best prediction (R-2) and predictive power (Q(2)) of Stairs, Pulling, Demolition, Terrain, and Rescue work capacities included field tests (R-2 = 0.73 to 0.84, Q(2) = 0.68 to 0.82). The best external validation was for Stairs work capacity (R-2 = 0.80) and worst for Demolition work capacity (R-2 = 0.40). In conclusion, field and laboratory tests could equally well predict physical work capacities for fire-fighting work tasks, and models excluding anthropometric data were valid. The predictive power was satisfactory for all included work tasks except Demolition.

  • 22.
    Lindberg, Ann-Sofie
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Oksa, Juha
    Physical Work Capacity-team, Finnish Institute of Occupational Health, Oulu, Finland.
    Gavhed, Désirée
    Department of Women’s and Children’s Health, Karolinska Institute.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Field tests for evaluating the aerobic work capacity of firefighters2013Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 7, s. e68047-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Working as a firefighter is physically strenuous, and a high level of physical fitness increases a firefighter's ability to cope with the physical stress of their profession. Direct measurements of aerobic capacity, however, are often complicated, time consuming, and expensive. The first aim of the present study was to evaluate the correlations between direct (laboratory) and indirect (field) aerobic capacity tests with common and physically demanding firefighting tasks. The second aim was to give recommendations as to which field tests may be the most useful for evaluating firefighters' aerobic work capacity. A total of 38 subjects (26 men and 12 women) were included. Two aerobic capacity tests, six field tests, and seven firefighting tasks were performed. Lactate threshold and onset of blood lactate accumulation were found to be correlated to the performance of one work task (rs = -0.65 and -0.63, p<0.01, respectively). Absolute (mL·min(-1)) and relative (mL·kg(-1)·min(-1)) maximal aerobic capacity was correlated to all but one of the work tasks (rs = -0.79 to 0.55 and -0.74 to 0.47, p<0.01, respectively). Aerobic capacity is important for firefighters' work performance, and we have concluded that the time to row 500 m, the time to run 3000 m relative to body weight (s·kg(-1)), and the percent of maximal heart rate achieved during treadmill walking are the most valid field tests for evaluating a firefighter's aerobic work capacity.

  • 23.
    Lindberg, Ann-Sofie
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Winternet, Boden.
    Oksa, Juha
    Physical Work Capacity Team, Finnish Institute of Occupational Health, Oulu, Finland.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Laboratory or field tests for evaluating firefighters' work capacity2014Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, nr 3, s. e91215-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Muscle strength is important for firefighters work capacity. Laboratory tests used for measurements of muscle strength, however, are complicated, expensive and time consuming. The aims of the present study were to investigate correlations between physical capacity within commonly occurring and physically demanding firefighting work tasks and both laboratory and field tests in full time (N = 8) and part-time (N = 10) male firefighters and civilian men (N = 8) and women (N = 12), and also to give recommendations as to which field tests might be useful for evaluating firefighters' physical work capacity. Laboratory tests of isokinetic maximal (IM) and endurance (IE) muscle power and dynamic balance, field tests including maximal and endurance muscle performance, and simulated firefighting work tasks were performed. Correlations with work capacity were analyzed with Spearman's rank correlation coefficient (rs). The highest significant (p<0.01) correlations with laboratory and field tests were for Cutting: IE trunk extension (rs = 0.72) and maximal hand grip strength (rs = 0.67), for Stairs: IE shoulder flexion (rs = −0.81) and barbell shoulder press (rs = −0.77), for Pulling: IE shoulder extension (rs= −0.82) and bench press (rs = −0.85), for Demolition: IE knee extension (rs = 0.75) and bench press (rs = 0.83), for Rescue: IE shoulder flexion (rs = −0.83) and bench press (rs = −0.82), and for the Terrain work task: IE trunk flexion (rs = −0.58) and upright barbell row (rs = −0.70). In conclusion, field tests may be used instead of laboratory tests. Maximal hand grip strength, bench press, chin ups, dips, upright barbell row, standing broad jump, and barbell shoulder press were strongly correlated (rs≥0.7) with work capacity and are therefore recommended for evaluating firefighters work capacity.

  • 24.
    Lindberg, Ann-Sofie
    et al.
    Winternet.
    Wiklund, Krister
    Andersson, Magnus
    Malm, Christer B.
    Firefighters' fit for duty score-model: Book of Abstracts2016Inngår i: 21st Annual Congress of the European College of Sport Science: Crossing borders through sport science, ECSS , 2016, artikkel-id 2322Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Physical capacity has previously been deemed important for firefighters’ physical work capacity, and evaluation of fitness for duty is common in the pre-hiring process. Various methods have been used to establish cut-off limits, i.e. normative data or expert judges. In accordance with government regulation, both full-time and part-time firefighters in Sweden have to pass a medical examination and a test of physical work capacity for permission to execute smoke diving. The physical work capacity test is a pass or fail test: dressed in firefighting protective clothes and breathing apparatus (total weight 24 ± 0.5 kg), six minutes walking with the incline at 8 degrees and treadmill speed of 4.5 km/h is performed. Inclusion of additional physical tests and appropriate cut-off limits is a decision taken by each individual municipality. The aim of the present study was to create a score model for evaluation of fitness for duty in the pre-hiring process of firefighters. Methods A total of 128 (64 men and 64 women) subjects: full-time firefighters, part-time firefighters and civilians, were included. Subjects performed five simulated firefighting work tasks and a selected battery six of physical tests including; 500 m rowing, grip strength, endurance bench press, track running 3000 m, standing broadjump and upright barbell row. The combined information from subjective evaluated cut-off limits, breakpoint estimation, checkpoint estimation and percentiles were used to create a score-model MO-PM30 Performance: Mixed Session 424 21ST ANNUAL CONGRESS OF THE EUROPEAN COLLEGE OF SPORT SCIENCE for evaluation of fit for duty. Results The models yielded various cut-off limits on the same physical test, depending on the work task investigated, but all tests were scored on a 1-11 scale. Consequently, the maximum total score was 66 and the minimum total score was 6. The recommended minimum total score of six tests is 36. Discussion In this study we created a score-model for evaluation of firefighters’ fit for duty in the pre-hiring process. When pre-hiring physical tests are performed, an easily conducted battery of physical tests is important in order to reduce costs but still maintain high validity and reliability. The score-model is easy to understand, performance gives the same score irrespectively of age and sex and makes it possible for the aspirants to prepare for the included physical tests. Since a specific physical test differs in importance in the prediction of simulated work task performance, the lack of performance in one physical test may not be fully compensated with a higher performance in another physical test. Simplifying and generalizing a method makes it practically usable at the detriment of accuracy on an individual level.

  • 25.
    Malm, Christer
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Anatomi.
    Exercise immunology: the current state of man and mouse.2004Inngår i: Sports Medicine, ISSN 0112-1642, Vol. 34, nr 9, s. 555-66Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanisms governing the body's response to physical exercise have been investigated from various perspectives including metabolism, nutrition, age and sex. Increased attention to the immune system during recent decades is reflected by a rapidly growing number of publications in the field. This article highlights the most recent findings and only briefly summarises more basic concepts already reviewed by others. Topics include Th1/Th2 cytokine balance, inoculation time, age and immune compensation. Some less investigated areas are discussed including studies in children, the environment and dendritic cells. Because physical exercise enhances some aspects and suppresses other aspects of immunity, the biological significance of alterations in the immune system are unknown. So far, no link between immunological alterations and infection rate has been established and infection after strenuous physical exercise is equally likely to be the result of exercising with an already established rather than a new infection. If there is an increased risk for infections with increased exercise duration and intensity, why do overtrained athletes not display the greatest risk for upper respiratory tract infections? Increased knowledge on immune system modulations with physical exercise is relevant both from a public health and elite athlete's point of view.

  • 26.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Susceptibility to infections in elite athletes: the S-curve2005Inngår i: Scandinavian journal of medicine & science in sports, ISSN 0905-7188, Vol. 16, nr 1, s. 4-6Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The susceptibility to upper respiratory tract infections (URTIs) after physical exercise has been described with a J-shaped curve, suggesting protection from infections with moderate exercise and increased risk for URTI`s in elite athletes. Several factors such as time of inoculation, previous infections, pathogen exposure, other stressors than exercise etc. can influence infection outcome. Observed infections in athletes can, therefore, be either the result of increased susceptibility to a novel pathogen, or more severe symptoms of an already established infection. Moreover, the definitions of "strenuous" exercise and "elite" athletes are equivocal, making comparisons between studies difficult.

    Because absence of infections is inevitable to become and maintain status as an elite athlete, it is suggested that there is an S-shaped relationship between exercise load and risk of infections. To become an elite athlete one has to possess state-of-the-art physique, including an immune system able to withstand infections even during severe physiological and psychological stress.

  • 27.
    Malm, Christer B.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Avdelningen för idrottsmedicin.
    Jakobsson, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Avdelningen för idrottsmedicin.
    Isaksson, Andreas
    Physical Activity and SportsReal Health Benefits: A Review with Insight into the Public Health of Sweden2019Inngår i: Sports, ISSN 2075-4663, Vol. 7, nr 5, artikkel-id 127Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Positive effects from sports are achieved primarily through physical activity, but secondary effects bring health benefits such as psychosocial and personal development and less alcohol consumption. Negative effects, such as the risk of failure, injuries, eating disorders, and burnout, are also apparent. Because physical activity is increasingly conducted in an organized manner, sport's role in society has become increasingly important over the years, not only for the individual but also for public health. In this paper, we intend to describe sport's physiological and psychosocial health benefits, stemming both from physical activity and from sport participation per se. This narrative review summarizes research and presents health-related data from Swedish authorities. It is discussed that our daily lives are becoming less physically active, while organized exercise and training increases. Average energy intake is increasing, creating an energy surplus, and thus, we are seeing an increasing number of people who are overweight, which is a strong contributor to health problems. Physical activity and exercise have significant positive effects in preventing or alleviating mental illness, including depressive symptoms and anxiety- or stress-related disease. In conclusion, sports can be evolving, if personal capacities, social situation, and biological and psychological maturation are taken into account. Evidence suggests a dose-response relationship such that being active, even to a modest level, is superior to being inactive or sedentary. Recommendations for healthy sports are summarized.

  • 28.
    Malm, Christer B.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Khoo, Nelson S.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Granlund, Irene
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Lindstedt, Emilia
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Hult, Andreas
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Autologous Doping with Cryopreserved Red Blood Cells - Effects on Physical Performance and Detection by Multivariate Statistics2016Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 6, artikkel-id e0156157Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The discovery of erythropoietin (EPO) simplified blood doping in sports, but improved detection methods, for EPO has forced cheating athletes to return to blood transfusion. Autologous blood transfusion with cryopreserved red blood cells (RBCs) is the method of choice, because no valid method exists to accurately detect such event. In endurance sports, it can be estimated that elite athletes improve performance by up to 3% with blood doping, regardless of method. Valid detection methods for autologous blood doping is important to maintain credibility of athletic performances. Recreationalmale (N = 27) and female (N = 11) athletes served as Transfusion (N = 28) and Control (N = 10) subjects in two different transfusion settings. Hematological variables and physical performance were measured before donation of 450 or 900 mL whole blood, and until four weeks after re-infusion of the cryopreserved RBC fraction. Blood was analyzed for transferrin, iron, Hb, EVF, MCV, MCHC, reticulocytes, leucocytes and EPO. Repeated measures multivariate analysis of variance (MANOVA) and pattern recognition using Principal Component Analysis (PCA) and Orthogonal Projections of Latent Structures (OPLS) discriminant analysis (DA) investigated differences between Control and Transfusion groups over time. Significant increase in performance (15 +/- 8%) and VO2max (17 +/- 10%) (mean +/- SD) could be measured 48 h after RBC re-infusion, and remained increased for up to four weeks in some subjects. In total, 533 blood samples were included in the study (Clean = 220, Transfused = 313). In response to blood transfusion, the largest change in hematological variables occurred 48 h after blood donation, when Control and Transfused groups could be separated with OPLS-DA (R-2 = 0.76/Q(2) = 0.59). RBC re-infusion resulted in the bestmodel (R-2 = 0.40/Q(2) = 0.10) at the first sampling point (48 h), predicting one false positive and one false negative. Over all, a 25% and 86% false positives ratio was achieved in two separate trials. In conclusions, autologous re-infusion of RBCs increased VO2max and performance as hypothesized, but hematological profiling by multivariate statistics could not reach the WADA stipulated false positive ratio of <0.001% at any time point investigated. A majority of samples remained within limits of normal individual variation at all times.

  • 29.
    Malm, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Celsing, F
    Friman, G
    Physical activity both enhances and depresses the immune system [Fysisk aktivitet både stimulerar och hämmar immunförsvaret]2005Inngår i: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, ISSN 237205, Vol. 102, nr 11, s. 867-873Artikkel, omtale (Annet (populærvitenskap, debatt, mm))
  • 30.
    Malm, Christer
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Anatomi.
    Celsing, Fredrik
    Friman, Göran
    Immune defense is both stimulated and inhibited by physical activity2005Inngår i: Läkartidningen, ISSN 0023-7205, Vol. 102, nr 11, s. 867-8, 870, 873Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [sv]

    Physical exercise may enhance some and depress other immune functions. The biological importance of these changes is not fully elucidated. Acute endurance exercise results in a relatively large redistribution of leukocytes between circulating blood and other tissues, as well as an increase in circulating cytokines. Some of these changes have been related to energy metabolism. A temporal correlation has been observed between altered immune functions and resistance to infections. A post-exercise infection can be either the result of a pre-exercise, sub-clinical infection amplified by the performed work or a novel infection, acquired during a period of decreased immune function shortly after exercise. Animal experiments have demonstrated that the susceptibility to infections after exercise depends on exercise intensity and duration, type of pathogen and time of inoculation. Exercise before inoculation with some bacterial agents can enhance resistance to infection, while exercise during an ongoing viral or bacterial infection worsens symptoms and enhances the risk for complications. Most studies demonstrate a deleterious effect of physical exercise in conjunction with infectious episodes.

  • 31.
    Malm, Christer
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Anatomi.
    Ekblom, Ö
    Ekblom, B
    Immune system alteration in response to increased physical training during a five day soccer training camp.2004Inngår i: International journal of sports medicine, ISSN 0172-4622, Vol. 25, nr 6, s. 471-6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Leukocyte and monocyte subpopulations were investigated in ten elite male soccer players before and after a 5-day training camp. It was hypothesized that with increased training intensity and duration, the immune system would show signs of depression. Blood samples were taken at rest before and after the training camp and cell surface antigens were investigated by four-colour flow cytometry. After five days of intensified training, there was a significant decrease in the number of T helper, T cytotoxic and B cells, the expression of CD11 b on leukocytes increased and the NK cell population did not change significantly. It is concluded that after a period of intensified training, soccer players may experience decreased T and B cell numbers in circulation, possibly affecting their capability to activate the immune system and resist infections. However, in contrast to the acute decrease in the number of circulating NK cells commonly observed after physical exercise, no change in this cell population was observed at rest after a period of intensified physical training. Exercise-induced immunological changes were highly differentiated between different leukocyte subpopulations.

  • 32.
    Malm, Christer
    et al.
    Umeå universitet.
    Ekblom, Ö
    Ekblom, B
    Immune system alteration in response to two consecutive soccer games.2004Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, Vol. 180, nr 2, s. 143-55Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AIM: Changes in leucocyte and monocyte subpopulations were investigated in 10 elite male soccer players aged 16-19 years. The purpose was to perform a descriptive study of immunological alterations in elite soccer players in response to two consecutive games separated by 20 h. It was hypothesized that in response to two games the players would show signs of short-term immunosuppression. METHODS: Blood samples were taken before the first soccer game, immediately after the second game and after 6, 24, 48 and 72 h. Cell surface antigens, testosterone and cortisol were investigated. RESULTS: During the first 6 h after the second game there was a significant increase in number of circulating neutrophils, mature (CD20+ CD5+) B cells and CD4/CD8 ratio. A significant decrease was observed in the number of natural killer (NK) cells, monocytes and adhesion on lymphocytes and monocytes. In a delayed phase, 48 h after the second game the expression of both adhesion and signalling molecules increased on lymphocytes and monocytes. Changes in adhesion and signalling molecules at 48 h correlated negatively to the subjects VO2max, suggesting larger immunological response to similar exercise in subjects with lower aerobic exercise capacity. CONCLUSION: In response to competitive soccer exercise some immunological variables are enhanced while others are depressed. Observed changes may serve a purpose in adaptation to exercise by signalling via adhesion.

  • 33.
    Malm, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Hadrevi, Jenny
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Bergström, Sven-Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Medicin.
    Pedrosa-Domellof, Fatima
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Antti, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Svensson, Michael
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Frängsmyr, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Evaluation of 2-D DIGE for skeletal muscle: Protocol and repeatability2008Inngår i: The Scandinavian Journal of Clinical & Laboratory Investigation, Vol. 68, nr 8, s. 793-800Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Proteomic analysis has the potential to yield vast amounts of data. The available proteomic methods have been hampered by methodological errors in quantification due to large gel-to-gel variations. The inclusion of an internal standard greatly reduces this variation, and therefore the purpose of this investigation was: 1) to develop a sample preparation protocol for human skeletal muscle for two-dimensional differentiated gel electrophoresis (DIGE) and 2) to investigate the repeatability of one particular system, the Ettan™ DIGE. To test repeatability, nine aliquots from the same homogenate were labelled with three different CyDye™ dyes (Cy2, Cy3, Cy5). Samples were run on 1824 cm gels, scanned with a Typhoon™ 9410 laser scanner and analysed in the DeCyder™ software. When selecting spots appearing only in triplicate (n = 1314), the mean error was 1.7 % (SD: 10.5 %; 95 % CI: 1.1-2.4 %). When setting the significance level to 99 %, no false-positive changes in protein volume ratios were detected. In the protocol presented here, only 0.5 mg tissue was used and separation of >2500 distinct protein spots in the pH range 3-11 and MW 10-200 kDa. Changes in protein abundance of <20 % could be detected. The method is especially useful when comparing muscle proteins between different conditions; for example, healthy and diseased tissue, before and after treatment or different exercise protocols.

  • 34.
    Malm, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin. 196808068917.
    Isaksson, Andreas
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Idrott: en viktig faktor för fysisk och psykisk hälsa2017Inngår i: Idrottens samhällsnytta: en vetenskaplig översikt av idrottsrörelsens mervärden för individ och samhälle / [ed] JohanFaskunger, Paul Sjöblom, Stockholm: Riksidrottsförbundet , 2017, , s. 229s. 21-39Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 35.
    Malm, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Lindberg, Ann-Sofie
    Brandmannens fysiska förmåga: Delrapport 2 - Fysiologiska tester2005Rapport (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    En viktig faktor för utgången av en räddningsinsats är räddningspresonalens fysiska prestationsförmåga. Det är därför av stor vikt att de fysiologiska krav som en brandman ska uppfylla är relevanta för yrkets arbetsuppgifter. Lika viktigt är det att resultaten på de tester av fysisk arbetskapacitet som genomförs inom Räddningstjänsten är direkt relaterade till arbetsprestation.

    Syftet med denna studie var att ta fram ett antal enkelt genomförbara tester av fysisk arbetskapacitet som är direkt relaterade till prestationen på de tyngsta arbetsmomenten inom Räddningstjänsten (se Brandmannens fysiska förmåga Delrapport 1 - Typinsatser). Fysisk prestationsförmåga kan var en begränsande faktor för dessa arbetuppgifters utförande.

    Andra möjliga begränsade faktorer vid dessa arbetsuppgifter så som psykologiska faktorer, teknisk kompetens eller logisk förmåga har inte behandlats i denna studie.

    Sammanlagt har 244 mätvariabler registrerats på 38 individer (9272 observationer) i samband med 7 arbetsuppgifter relaterade till Räddningstjänst. Individerna var indelade i 4 grupper: Heltidsbrandmän, Deltidsbrandmän, Män och Kvinnor. De arbetsuppgifter som studerats är: Håltagning i yttertak, Losstagning ur bil, Slangkorgsbärning i terräng, Slangkorgsbärning i trapphus, Slangdragning, Rivning av innertak och Docksläpning.

    Resultat blev att prestationen på 5 av de 7 studerade arbetsuppgifter kan beskrivas med hjälp av 8 relativt enkelt genomförbara mätningar. Dessa mätningar är: Kroppslängd, Kroppsvikt, Maximal handgreppsstyrka, Bänkpress, Lyft till hakan, Stående längdhopp, Löpning 3000 m och Rodd 500 m. Resultaten visar även att maximal syreupptagning kan bestämmas med relativt stor säkerhet från dessa 8 mätningar. Inga av dessa resultat diskriminerar någon av de studerade grupperna.

    Rullbandstest (AFS 1995:1) och Cykeltest 200 W underskattar kvinnors och överskattar mäns aeroba arbetskapacitet och bör därför inte användas som mått på detta, utan även i fortsättningen användas enbart för medicinsk bedömning.

    Resultaten på testerna kan ligga till grund för en relevant och objektiv bedömning av personers fysiska prestationsförmåga vid nyrekrytering och återtestning av personal inom Räddningstjänsten.

  • 36.
    Malm, Christer
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Anatomi.
    Sjödin, Bertil
    Sjöberg, Berit
    Lenkei, Rodica
    Renström, Per
    Lundberg, Ingrid E
    Ekblom, Björn
    Leukocytes, cytokines, growth factors and hormones in human skeletal muscle and blood after uphill or downhill running.2004Inngår i: The Journal of physiology, ISSN 0022-3751, Vol. 556, nr Pt 3, s. 983-1000Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Muscular adaptation to physical exercise has previously been described as a repair process following tissue damage. Recently, evidence has been published to question this hypothesis. The purpose of this study was to investigate inflammatory processes in human skeletal muscle and epimysium after acute physical exercise with large eccentric components. Three groups of subjects (n= 19) performed 45 min treadmill running at either 4 deg (n= 5) or 8 deg (n= 9) downhill or 4 deg uphill (n= 5) and one group served as control (n= 9). One biopsy was taken from each subject 48 h post exercise. Blood samples were taken up to 7 days post exercise. Compared to the control group, none of the markers of inflammation in muscle and epimysium samples was different in any exercised group. Only subjects in the Downhill groups experienced delayed onset of muscle soreness (DOMS) and increased serum creatine kinase activity (CK). The detected levels of immunohistochemical markers for T cells (CD3), granulocytes (CD11b), leukaemia inhibitory factor (LIF) and hypoxia-inducible factor 1beta (HIF-1beta) were greater in epimysium from exercised subjects with DOMS ratings >3 (0-10 scale) compared to exercised subjects without DOMS but not higher than controls. Eccentric physical exercise (downhill running) did not result in skeletal muscle inflammation 48 h post exercise, despite DOMS and increased CK. It is suggested that exercise can induce DOMS by activating inflammatory factors present in the epimysium before exercise. Repeated physical training may alter the content of inflammatory factors in the epimysium and thus reduce DOMS.

  • 37.
    Malm, Christer
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Yu, Ji-Guo
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Exercise-induced muscle damage and inflammation: re-evaluation by proteomics2012Inngår i: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 138, nr 1, s. 89-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using proteomics combined with immunohistochemistry (IHC), we re-evaluated our previous hypothesis that voluntary eccentric exercise does not result in inflammation or necrosis while it does lead to muscular adaptation/remodeling through Z-band related proteins. Muscle biopsies from m. vastus lateralis were taken from five control and five exercised subjects 48 h after 45 min of downhill running. General muscle morphology was examined using histology and histochemistry. Proteomics was used to reveal protein profiles and novel proteins. IHC with specific antibody against three Z-band related proteins identified by proteomics was also performed. General morphology showed no muscle degeneration or inflammation in any exercised biopsy. Proteomics revealed that out of 612 individual protein spots, the exercised biopsy presented three proteins with significant (p < 0.05) higher expression ratio and four proteins of lower ratio compared to controls. Four of the proteins desmin, actin, Rab-35 and LDB3 are Z-band related; the former two have long been the focus of interest and were found to be up-regulated in the study; the latter two are Z-band assembly/stabilization protein and were for the first time observed to be down-regulated in exercised muscles. The other three proteins are related with either cellular metabolism or calcium homeostasis and none is related with muscle necrosis or inflammation. IHC observations that both desmin and actin were increased whereas LDB3 was completely absent in some focal areas are consistent with proteomic results and with our previous observations. The results of the study confirmed our previous findings and therefore strengthened the hypothesis that voluntary eccentric exercise does not cause human muscle necrosis or inflammation; instead, muscular remodeling occurs specifically through Z-band related proteins.

  • 38. Mårtensson, Sandra
    et al.
    Nordebo, Kristina
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    High Training Volumes are Associated with a Low Number of Self-Reported Sick Days in Elite Endurance Athletes2014Inngår i: Journal of Sports Science and Medicine (JSSM), ISSN 1303-2968, Vol. 13, nr 4, s. 929-933Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It has been proposed that high exercise loads increase the risk of infection, most frequently reported as upper respiratory tract infections, by suppressing the immune system. Most athletes will not train when experiencing sickness due to the fear of health complications. However, high training volumes are incompatible with high rates of non-training days, regardless of the cause. The purpose of this observational study was to examine the relationship between self-reported, exercise-constraining days of sickness (days when the athlete decided not to train due to symptoms of disease, either self-reported or by a physician) and the volumes of exercise training in elite endurance athletes by analyzing data from training logs kept for several years. The subjects included 11 elite endurance athletes (8 male, 3 female) competing at national and international levels in cross-country skiing, biathlon and long-distance running. Training logs available from these 11 subjects added to a total of 61 training years. The number of training hours per year (462, 79-856; median, range) was significantly and negatively correlated to the reported number of days not training due to sickness (15, 0-164) by a 3rd degree polynomial regression (R-2 = 0.48, F ratio = 18, p < 0.0001). We conclude that elite endurance athletes can achieve high training volumes only if they also experience few sickdays.

  • 39.
    Nilsson, Robert
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Lindberg, Ann-Sofie
    Theos, Apostolos
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Ferguson, Richard A.
    School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Idrottsmedicin.
    Aerobic Variables for Prediction of Alpine Skiing Performance: A Novel Approach2018Inngår i: Sports Medicine International Open, ISSN 2367-1890, Vol. 2, nr 4, s. E105-E112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to investigate the predictive power of aerobic test results and anthropometric variables on FIS-ranking of junior elite alpine skiers. Results from twenty-three male and female adolescent elite alpine skiers from two seasons were included in the multivariate statistical models. Physical work capacity was determined by V̇O2peak, blood lactate concentration ([HLa]b), and heart rate (HR) during ergometer cycling. Anthropometric variables were body stature, body weight and calculated BMI. No significant correlation between competitive performance and aerobic work capacity or anthropometric data was observed neither in male nor female adolescent skiers. Pre-season physical tests and anthropometric data could therefore not predict end-season FIS-ranking. The best regression (R2) and prediction (Q2) models of FIS slalom (SL) and giant slalom (GS) rank reached R2=0.51 to 0.86, Q2=−0.73 to 0.18, indicating no valid models. This study could not establish V̇O2peak and other included variables as predictors of competitive performance. When combining results from commonly used tests for alpine skiers, and applying multivariate statistical models, investigated tests seems of limited used for athletes, coaches, and ski federations. Performance-specific pre-season tests must be developed and validated for prediction of performance and guidance of exercise training.

  • 40.
    Nilsson, Robert
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Avdelningen för idrottsmedicin.
    Theos, Apostolos
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Avdelningen för idrottsmedicin.
    Lindberg, Ann-Sofie
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Avdelningen för idrottsmedicin. Winternet, Boden, Sweden.
    Ferguson, Richard A.
    School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom.
    Malm, Christer B.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Avdelningen för idrottsmedicin.
    Individual Profiling for Prediction of Competitive Performance in Alpine SkiingManuskript (preprint) (Annet vitenskapelig)
  • 41.
    Nordström, Anna
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Rehabiliteringsmedicin.
    Högström, Gabriel
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Eriksson, Anders
    Department of Health Sciences, Luleå University of Technology, Luleå.
    Bonnerud, Patrik
    Department of Health Sciences, Luleå University of Technology, Luleå.
    Tegner, Yelverton
    Department of Health Sciences, Luleå University of Technology, Luleå.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Winternet, Boden, Idrottsmedicin.
    Higher muscle mass but lower gynoid fat mass in athletes using anabolic androgenic steroids2012Inngår i: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287, Vol. 26, nr 1, s. 246-250Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nordstrom, A, Hogstrom, G, Eriksson, A, Bonnerud, P, Tegner, Y, and Malm, C. Higher muscle mass but lower gynoid fat mass in athletes using anabolic androgenic steroids. J Strength Cond Res 26(1): 246-250, 2012-This study evaluated the relationship between anabolic androgenic steroid (AAS) use and body constitution. Dual-energy x-ray absorptiometry was used to measure bone mineral density (BMD, g.cm(-2)) of the total body, arms, and legs. Total gynoid and android fat mass (grams) and total lean mass (grams) were measured in 10 strength trained athletes (41.4 +/- 7.9 years) who had used AASs for 5-15 years (Doped) and 7 strength trained athletes (29.4 +/- 6.2 years) who had never used AASs (Clean). Seventeen sedentary men (30.3 +/- 2.1 years) served as Controls. Doped athletes had significantly more lean body mass (85.5 +/- 3.8 vs. 75.3 +/- 2.5 vs. 60.7 +/- 1.9, p < 0.001) and a greater index of fat-free/fat mass (5.8 vs. 2.6 vs. 2.5, p < 0.001) compared with Clean athletes and Controls. Doped athletes also had significantly less gynoid fat mass compared with that of Clean athletes (2.8 +/- 0.4 vs. 4.8 +/- 0.2 kg, p = 0.02). There were no differences in BMD between the athletes (p = 0.39-0.98), but both groups had significantly higher BMDs at all sites compared with that of Controls (p = 0.01 to <0.001). Thus, long-term AAS use seems to alter body constitution, favoring higher muscle mass and reduced gynoid fat mass without affecting BMD.

  • 42. Piedrahita, Hugo
    et al.
    Oksa, Juha
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Rintamäki, Hannu
    Health problems related to working in extreme cold conditions indoors.2008Inngår i: International Journal of Circumpolar Health, ISSN 1239-9736, E-ISSN 2242-3982, Vol. 67, nr 2-3, s. 279-87Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVES: To identify health problems among workers performing cleaning, maintenance and machine operation tasks inside cold storage rooms with temperatures between -43 degrees C and -62 degrees C in a freeze drying coffee company. STUDY DESIGN: Descriptive study. METHODS: All 24 workers working inside the cold stores participated in the study. A questionnaire about cold-related health problems and the standardized Nordic questionnaire assessing muscle complaints were completed by all exposed workers. A physical examination was performed on each worker. RESULTS: The most relevant cold-related health problem was episodic finger symptoms (50%), followed by respiratory symptoms (21%), peripheral circulation symptoms (20%), and repeated pain in the musculoskeletal system (12%). Two subjects had a previous diagnosis of Raynaud's phenomenon (RP). The prevalence of musculoskeletal complains in the neck and low back was 21% in each. CONCLUSIONS: The prevalence found for various complaints among the freeze drying coffee workers implies that the cold conditions inside cold stores may present a real risk of cold-related health problems and, due to lowered concentration level, for injuries, too. Greater efforts should be made to minimize the cold exposure by designing automation processes to prevent continuous exposure to cold during freeze drying process. In addition, improving the cold-protective clothing and guaranteeing its appropriate use will reduce health risks.

  • 43. Piedrahita, Hugo
    et al.
    Oksa, Juha
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Sormunen, Erja
    Rintamäki, Hannu
    Effects of cooling and clothing on vertical trajectories of the upper arm and muscle functions during repetitive light work.2008Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 104, nr 2, s. 183-91Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present study was designed to find out if cooling and/or clothing affect the vertical trajectories and muscle function of the upper arm during repetitive light work. Twelve female subjects performed a one-handed lifting task for 60 min while standing in front of a table with six target angles (30 degrees to 220 degrees ). The experiment was carried out in a climatic chamber in three different conditions: at 10 degrees C (C), at 25 degrees C (TN), and at 10 degrees C dressed in cold-protective clothing (C(p)). Skin and rectal temperatures were measured continuously. The vertical trajectories of the head, shoulder, elbow, and wrist on the right side of the body were recorded. Muscular strain (averaged EMG, a-EMG) and EMG gaps in eight muscles on the right upper arm were measured. The variation of the vertical trajectory amplitude of the upper arm measured from the elbow was significantly higher (at 200 degrees ) both at C and C(p) (50 and 25% respectively) and in shoulder (at 220 degrees angle) at C (33%) compared with TN (P < 0.05). Both C and C(p) increased a-EMG and reduced the number and duration of EMG gaps significantly in all muscles studied. In conclusion, in repetitive tasks the high mean vertical trajectory and changes in the amplitude of the trajectory of the upper arm at C and C(p) compared with TN were associated with increased muscular strain and reduced number of EMG gaps (more continuous activation of given muscle fibers). The changes in trajectories may serve as indicator of a risk for local muscle fatigue.

  • 44.
    Piedrahita, Hugo
    et al.
    Luleå University of Technology Human Work Sciences Department 97187 Luleå Sweden.
    Oksa, Juha
    Finnish Institute of Occupational Health Physical Work Capacity Team 90220 Oulu Finland.
    Rintamäki, Hannu
    Finnish Institute of Occupational Health Physical Work Capacity Team 90220 Oulu Finland.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Effect of local leg cooling on upper limb trajectories and muscle function and whole body dynamic balance2009Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 105, nr 3, s. 429-438Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study was designed to find out if local leg cooling affects muscle function and trajectories of the upper limb during repetitive light work as well as capability to maintain dynamic balance. Nine healthy female subjects performed repetitive lifting task with right hand for 60 min while standing in front of a table with six target angles (30 degrees -220 degrees ) and with the legs inside a container with 15 degrees C cold water (Cold condition, C) or without water (Normal condition, N). Muscle temperature of the medial aspect of the gastrocnemius, rectal, and skin temperatures were measured continuously. The trajectories of the right upper limb were recorded with a 3D motion analysis system. Muscular strain (averaged EMG, a-EMG) and EMG gaps in eight muscles of the right upper limb were measured. End point excursion depicting the ability to maintain dynamic balance was measured before and after each experiment. Leg cooling decreased significantly (P < 0.05) the muscle and the mean skin temperature in C compared with N (6.7 and 2.2 degrees C, respectively). No marked changes in the trajectories or EMG activity were observed between the different environmental conditions. The end point excursion was significantly (P < 0.05) reduced in C compared with N and a positive correlation between excursion and muscle temperature was found at the end of the working period in C. In conclusion, local leg cooling did not affect upper limb muscle function or trajectories, but ability to maintain dynamic balance was reduced.

  • 45.
    Yu, J-G
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Thornell, Lars-Eric
    Eccentric contractions leading to DOMS do not cause loss of desmin nor fibre necrosis in human muscle.2002Inngår i: Histochemistry and Cell Biology, ISSN 0948-6143, Vol. 118, nr 1, s. 29-34Artikkel i tidsskrift (Fagfellevurdert)
  • 46.
    Yu, Ji-Guo
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Bonnerud, Patrik
    Department of Health Sciences, Luleå University of Technology, Luleå.
    Eriksson, Anders
    Department of Health Sciences, Luleå University of Technology, Luleå.
    Stål, Per S.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Tegner, Yelverton
    Department of Health Sciences, Luleå University of Technology, Luleå.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Effects of long term supplementation of anabolic androgen steroids on human skeletal muscle2014Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, nr 9, artikkel-id e105330Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of long-term (over several years) anabolic androgen steroids (AAS) administration on human skeletal muscle are still unclear. In this study, seventeen strength training athletes were recruited and individually interviewed regarding self-administration of banned substances. Ten subjects admitted having taken AAS or AAS derivatives for the past 5 to 15 years (Doped) and the dosage and type of banned substances were recorded. The remaining seven subjects testified to having never used any banned substances (Clean). For all subjects, maximal muscle strength and body composition were tested, and biopsies from the vastus lateralis muscle were obtained. Using histochemistry and immunohistochemistry (IHC), muscle biopsies were evaluated for morphology including fiber type composition, fiber size, capillary variables and myonuclei. Compared with the Clean athletes, the Doped athletes had significantly higher lean leg mass, capillary per fibre and myonuclei per fiber. In contrast, the Doped athletes had significantly lower absolute value in maximal squat force and relative values in maximal squat force (relative to lean body mass, to lean leg mass and to muscle fiber area). Using multivariate statistics, an orthogonal projection of latent structure discriminant analysis (OPLS-DA) model was established, in which the maximal squat force relative to muscle mass and the maximal squat force relative to fiber area, together with capillary density and nuclei density were the most important variables for separating Doped from the Clean athletes (regression  =  0.93 and prediction  =  0.92, p<0.0001). In Doped athletes, AAS dose-dependent increases were observed in lean body mass, muscle fiber area, capillary density and myonuclei density. In conclusion, long term AAS supplementation led to increases in lean leg mass, muscle fiber size and a parallel improvement in muscle strength, and all were dose-dependent. Administration of AAS may induce sustained morphological changes in human skeletal muscle, leading to physical performance enhancement.

  • 47.
    Yu, Ji-Guo
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Malm, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Thornell, Lars-Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    Eccentric contractions leading to DOMS do not cause loss of desmin nor fibre necrosis in human muscle.2002Inngår i: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 118, nr 1, s. 29-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High force eccentric muscle contractions can result in delayed onset muscle soreness (DOMS), prolonged loss of muscle strength, decreased range of motion, muscle swelling and an increase of muscle proteins in the blood. At the ultrastructural level Z-line streaming and myofibrillar disruptions have been taken as evidence for muscle damage. In animal models of eccentric exercise-induced injury, disruption of the cytoskeleton and the sarcolemma of muscle fibres occurs within the first hour after the exercise, since a rapid loss of staining of desmin, a cytoskeletal protein, and the presence of fibronectin, a plasma and extracellular protein, are observed within the muscle fibres. In the present study, biopsies from subjects who had performed different eccentric exercises and had developed DOMS were examined. Our aim was to determine whether eccentric exercise leading to DOMS causes sarcolemmal disruption and loss of desmin in humans. Our study shows that even though the subjects had DOMS, muscle fibres had neither lost staining for desmin nor contained plasma fibronectin. This study therefore does not support previous conclusions that there is muscle fibre degeneration and necrosis in human skeletal muscle after eccentric exercise leading to DOMS. Our data are in agreement with the recent findings that there is no inflammatory response in skeletal muscle following eccentric exercise in humans. In combination, these findings should stimulate the search for other mechanisms explaining the functional and structural alterations in human skeletal muscle after eccentric exercise.

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